Joni Sledge, Member Of 'We Are Family' Group Sister Sledge, Dead At 60

SHEFFIELD, UNITED KINGDOM - JULY 26: Joni Sledge of Sister Sledge performs on stage at Tramlines Festival at (venue) on July 26, 2014 in Sheffield, United Kingdom. (Photo by Andrew Benge/Redferns via Getty Images)

Joni Sledge, a founding member of the “We Are Family” disco quartet Sister Sledge, was found dead Friday at her home in Phoenix, Arizona. She was 60.

Publicist Biff Warren confirmed Sledge’s death, telling CNN that the cause is unclear. The singer’s family posted about her death on the group’s official Facebook account.

Born in Philadelphia, Joni was the second-oldest daughter of a Broadway tap dancer and an actress. She and her three sisters ― Debbie, Kim and Kathy ― performed in church before forming a touring group in 1971.

In 1979, working with masterminds of Chic, Nile Rodgers and Bernard Edwards, they hit the big time with the album “We Are Family,” whose title track peaked at No. 2 on the Billboard Top 100 chart and spawned many cover versions.

Sister Sledge re-recorded the song with Patti LaBelle, Queen Latifah, Diana Ross and other artists as a Sept. 11 charity endeavor. Spike Lee directed the corresponding music video. Today, “We Are Family” is a staple of wedding playlists. In 2008, it was inducted into the Grammy Hall of Fame.

Nothing could match the success of “We Are Family,” but Sister Sledge found hits in “He’s the Greatest Dancer,” “Got to Love Somebody” and a cover of Mary Wells’ “My Guy.” The band performed a medley on a 1984 episode of “The Jeffersons,” including “We Are Family” and Stevie Wonder’s “As.”

Eldest sister Kathy left in 1989 to pursue a solo career, but joined her family for the Sept. 11 tribute and a 2015 performance at the World Meeting of Families festival, where Pope Francis was the guest of honor.

The group remained popular in the U.K. and had several concerts booked throughout 2017, including one as soon as March 18.